I thought FFVI was really effective with what it was able to convey with it's sprites and lack of voice acting. Locke's desperation trying to revive Rachel, Celes's dispair when you let Cid die and her act of attempted suicide, and themes such teenage pregnancy(Katarin and Duane), the different facets of what "love" means(love between those you care for, relationships that go through rocky situations and trust issues, as well that true love is not always love between "lovers" but can be anything from brotherly bonds as well as a woman's unconditional love towards a town of orphans). One of the many reasons it's still my favorite Final Fantasy game of all time. I don't think Square has came close to attempting to address similar issues with the FF series since then(maybe to play it more safe).
Yeah, what the creators of Final Fantasy 6 were able to accomplish with a few megabytes of space only becomes more impressive as time goes by, while most of the following games in the series just played it increasingly safe, relying on cutting edge visuals and style rather than a real soul. Heck the last (imo) really great game in the series, IX, was originally going to be a spinoff instead of a main series game. Call me crazy but I think the last vestiges of the real Squaresoft ended when Sakaguchi left, and I don't just mean the name change.